{"gene":"SERPINB5","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":2000,"finding":"Wild-type p53 directly activates maspin transcription by binding to a p53 consensus-binding site in the maspin promoter, as demonstrated by promoter reporter assays and gel-shift experiments; DNA-damaging agents induced maspin expression in cells with wild-type p53 but not mutant p53.","method":"Adenoviral p53 overexpression, promoter reporter assay, gel-shift (EMSA), RT-PCR in prostate and breast cancer cell lines","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (EMSA, promoter reporter, functional rescue), replicated across multiple cell lines","pmids":["10692390"],"is_preprint":false},{"year":2004,"finding":"p63 (specifically TAp63) is a critical transcriptional activator of maspin in lung cancer cells, binding to the previously identified p53-binding site on the maspin promoter, as shown by gel-shift and chromatin immunoprecipitation assays.","method":"Transient transfection, promoter reporter assay, EMSA, ChIP","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1–2 — orthogonal methods (ChIP + EMSA + reporter assay) in a single rigorous study","pmids":["15466179"],"is_preprint":false},{"year":2007,"finding":"Nuclear IKKα activated by RANKL represses maspin transcription in prostate epithelial cells; a mutation preventing IKKα activation led to elevated maspin expression and reduced metastasis in TRAMP mice, with ablation of maspin restoring metastatic activity.","method":"Genetic mouse model (TRAMP), IKKα knock-in mutation, nuclear IKKα translocation assay, epistasis rescue experiment","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1–2 — in vivo genetic epistasis in mouse model plus molecular rescue, high-citation foundational study","pmids":["17377533"],"is_preprint":false},{"year":2006,"finding":"Maspin binds to pro-uPA (K_d ~270 nM) via its reactive site loop (RSL), with Arg340 (P1' site) critical for binding; this interaction inhibits plasmin-mediated pro-uPA cleavage and promotes internalization of uPA/uPAR, thereby stabilizing focal adhesion contacts and retarding cell detachment.","method":"Biochemical binding assay (fluorescence), site-directed mutagenesis (R340A), co-localization, cell detachment assay, LRP co-IP","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 1 — direct binding measured with K_d, mutagenesis confirming critical residue, multiple orthogonal functional assays","pmids":["16618739"],"is_preprint":false},{"year":2007,"finding":"Maspin binds uPA and tPA through an exosite on maspin near but outside its reactive center loop, with K_d values 300–600 nM; the binding site on tPA does not involve the proteinase active site, and RCL mutation (Arg340) does not abolish binding, indicating exosite–exosite interactions.","method":"Fluorescence binding assays (intrinsic and extrinsic), RCL mutagenesis, binding to S195A tPA already complexed with PAI-1","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — direct biophysical binding measurement with mutagenesis dissecting binding site","pmids":["17510061"],"is_preprint":false},{"year":2010,"finding":"The G α-helix of maspin is essential and sufficient for inhibiting cell migration and mediating effects on cell adhesion; these effects are dependent on β1 integrins, as demonstrated by point mutations and a 15-mer G-helix peptide mimicking full-length maspin activity.","method":"Site-directed mutagenesis, peptide reconstitution, cell migration assay, cell adhesion assay, β1-integrin blocking","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — mutagenesis + peptide reconstitution + integrin blocking providing convergent mechanistic evidence","pmids":["20837467"],"is_preprint":false},{"year":2007,"finding":"Maspin inhibits Rac1 and Cdc42 GTPase activity (but not RhoA) to control mammary tumor cell migration; the reactive site loop (RSL) of maspin is required for this inhibition, and downstream JNK kinase activity and AP-1 transcription are suppressed.","method":"GST-PAK and GST-Rho binding pull-down for GTP-bound GTPases, RSL deletion/point-mutation analysis, immuno-kinase assay, AP-1 reporter assay","journal":"Cell motility and the cytoskeleton","confidence":"High","confidence_rationale":"Tier 1–2 — direct GTPase pull-down plus mutagenesis plus downstream signaling readouts","pmids":["17301947"],"is_preprint":false},{"year":2003,"finding":"Maspin inhibits uPA-mediated extracellular matrix degradation and collagen remodeling in vitro, and maspin-expressing DU145 prostate cancer cells injected into human fetal bone implants show decreased tumor growth, reduced osteolysis, decreased angiogenesis, increased fibrosis, and glandular redifferentiation in vivo.","method":"In vitro ECM/collagen degradation assays, maspin-transfectant xenograft model in immunodeficient mice with human fetal bone","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean gain-of-function in vivo model with specific phenotypic readouts (osteolysis, angiogenesis, fibrosis)","pmids":["12788977"],"is_preprint":false},{"year":2005,"finding":"Maspin overexpression reduces Bcl-2 protein levels and increases Bax protein levels post-translationally, leading to increased cytochrome c release and apoptosis in mammary tumor cells under staurosporine and serum starvation; the effect is intracellular and is partially blocked by caspase-8 and caspase-9 inhibitors.","method":"Stable maspin-expressing transfectants, TUNEL assay, Western blot, RPA for Bcl-2 family, caspase inhibitor experiments","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO/OE with multiple readouts but single lab","pmids":["15907209"],"is_preprint":false},{"year":2005,"finding":"Targeted intravascular expression of maspin in endothelial cells induces endothelial cell apoptosis in vitro and in vivo, disrupting tumor-induced angiogenesis; the pro-apoptotic effect requires the RSL region of maspin and is accompanied by changes in Bcl-2 family gene expression and is blocked by caspase inhibitors and Bcl-2 overexpression.","method":"Adenoviral maspin delivery in mice bearing mammary tumors, in vitro HUVEC apoptosis assay, RSL-deletion mutant, Bcl-2 overexpression rescue, caspase inhibitor experiments","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1–2 — in vivo delivery plus in vitro mechanistic dissection with mutagenesis and genetic rescue","pmids":["15688005"],"is_preprint":false},{"year":2003,"finding":"Maspin regulates cell motility through the Rho GTPase pathway: exogenous recombinant maspin decreases Rac1 activity within 4 h and reduces its effector PAK1 within 12 h in MDA-MB-231 breast cancer cells; adhesion increase is mediated by PI3K/ERK pathways and is abrogated by LY294002.","method":"Recombinant maspin treatment, stable transfection, Rac1 pull-down, PI3K inhibitor (LY294002), ERK kinase assay, focal adhesion staining","journal":"Cancer biology & therapy","confidence":"Medium","confidence_rationale":"Tier 2 — multiple signaling readouts with pharmacological epistasis, single lab","pmids":["14508113"],"is_preprint":false},{"year":2011,"finding":"Maspin directly inhibits HDAC1, increasing Ku70 acetylation and dissociation of Bax from Ku70, thereby promoting Bax translocation to mitochondria and apoptosis in cancer cells.","method":"Co-IP (maspin–Ku70 interaction), HDAC1 activity assay, Ku70 acetylation Western blot, Bax–Ku70 dissociation assay, cell death measurements","journal":"International journal of molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical interaction plus functional consequence, single lab","pmids":["22076034"],"is_preprint":false},{"year":2008,"finding":"Maspin suppresses hypoxia-induced prostate cancer cell survival and tumor vascularity by targeting Akt and focal adhesion kinase (FAK) activation, as shown in maspin-overexpressing DU-145 cells exposed to 1% O₂ and in in vivo tumor studies.","method":"Maspin-overexpressing stable transfectants, hypoxia exposure (1% O₂), Akt/FAK phosphorylation Western blot, in vivo tumor implantation","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — gain-of-function in vitro and in vivo with signaling readouts, single lab","pmids":["18931702"],"is_preprint":false},{"year":2009,"finding":"In response to hypoxia, cytoplasmic PTEN prevents Mdm2 nuclear localization (by attenuating Akt) while nuclear PTEN complexes with p53 to coordinately induce maspin transcription; loss of PTEN or p53 individually attenuates hypoxia-induced maspin expression in glioblastoma cells.","method":"PTEN/p53 knockdown and reconstitution in U87 cells, subcellular fractionation, Co-IP (PTEN–p53 complex), in vivo xenograft IHC","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with Co-IP and in vivo validation, single lab","pmids":["19221500"],"is_preprint":false},{"year":2012,"finding":"Snail transcription factor directly represses maspin promoter activity by binding to the maspin promoter, as confirmed by ChIP; Snail overexpression increases and Snail knockdown decreases maspin expression, with corresponding changes in migration and invasion in prostate cancer cells.","method":"Luciferase reporter assay, ChIP, RT-PCR, Western blot, siRNA knockdown, stable overexpression, migration/invasion assays","journal":"BMC cancer","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus reporter plus functional assays, single lab","pmids":["22857708"],"is_preprint":false},{"year":2010,"finding":"PAR-1 (thrombin receptor) negatively regulates maspin transcription in metastatic melanoma by decreasing binding of Ets-1 and c-Jun to the maspin promoter via reduced CBP/p300 levels and increased p38 activity; PAR-1 silencing restored maspin expression, reduced invasion, tumor growth, and experimental lung metastasis.","method":"PAR-1 siRNA nanoliposome delivery, ChIP for Ets-1/c-Jun at maspin promoter, CBP/p300 and p38 expression analysis, in vivo lung metastasis model, maspin rescue experiments","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — ChIP, in vivo epistasis rescue, and multiple orthogonal methods in a single study","pmids":["21187389"],"is_preprint":false},{"year":2012,"finding":"Maspin regulates cell cycle progression by influencing CDC25C and CDK1 activity; maspin downregulation (by shRNA or E2F1-DP1 overexpression) in MKN45 cells accelerated cell cycle progression with increased active CDC25C and decreased inactive CDK1, while maspin upregulation had the opposite effect.","method":"shRNA knockdown, stable overexpression, cell cycle analysis, CDC25C/CDK1 phosphorylation Western blot, promoter haplotype reporter assay","journal":"Carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 — gain- and loss-of-function with defined molecular readouts, single lab","pmids":["22962304"],"is_preprint":false},{"year":2011,"finding":"SerpinB5/maspin interacts with KHDRBS3 and FBXO32 in gastric cancer cells, as identified by yeast two-hybrid screening and validated by co-immunoprecipitation; KHDRBS3 also interacts with FBXO32 mRNA (RNA Co-IP), and changes in SerpinB5 expression affect FBXO32 mRNA levels through KHDRBS3 protein.","method":"Yeast two-hybrid, co-immunoprecipitation, RNA co-immunoprecipitation, Western blot, real-time PCR","journal":"Oncology reports","confidence":"Medium","confidence_rationale":"Tier 3 — reciprocal Co-IP plus RNA Co-IP, but functional consequences of complex incompletely established","pmids":["21725612"],"is_preprint":false},{"year":2008,"finding":"A Pro176Ser polymorphism in maspin located near the reactive site loop reduces its tumor suppressor function: cells expressing Ser176 maspin showed decreased apoptosis, increased colony formation, and higher in vivo tumor formation rate compared to Pro176 maspin.","method":"Stable expression of polymorphic variants, apoptosis assay, colony formation assay, mouse tumor formation assay, structural modeling","journal":"International journal of molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — direct functional comparison of polymorphic variants in vitro and in vivo, single lab","pmids":["18698492"],"is_preprint":false},{"year":2002,"finding":"Maspin gene silencing in breast cancer cells is caused by CpG promoter hypermethylation and histone deacetylation; treatment with 5-aza-2'-deoxycytidine and/or trichostatin A restores maspin promoter activity and expression in maspin-negative breast cancer cell lines.","method":"Promoter reporter assay, 5-aza-dC treatment, TSA treatment, RT-PCR","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological demethylation/HDAC inhibition experiments with promoter reporter, replicated in multiple cell lines","pmids":["12220518"],"is_preprint":false},{"year":2003,"finding":"Maspin expression in human pancreatic carcinoma cells is activated by epigenetic derepression: maspin-positive pancreatic cancer cells have unmethylated promoters with hyperacetylated H3/H4 histones, whereas maspin-negative cells have methylated promoters with hypoacetylated histones; 5-aza-dC treatment activates maspin in negative lines.","method":"Bisulfite genomic sequencing, ChIP (H3/H4 acetylation), 5-aza-dC treatment, RT-PCR","journal":"Neoplasia (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 — bisulfite sequencing + ChIP + pharmacological intervention, orthogonal epigenetic characterization","pmids":["14670180"],"is_preprint":false},{"year":2004,"finding":"Tamoxifen induces maspin expression through estrogen receptor alpha (ERα) but not ERβ; the ERα N-terminal AF-1 domain is required for basal maspin transcription and the LBD-AF2 domain is required for tamoxifen-induced activation; binding occurs via cofactor recruitment to a region between -90 and +87 bp, not through the HRE site.","method":"Promoter reporter assay, ERα/ERβ reconstitution, ERα deletion/point mutants, transient transfection in multiple cell lines","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 — systematic domain mutant analysis with reporter assay, single lab","pmids":["15145521"],"is_preprint":false},{"year":2008,"finding":"IFIXα induces maspin expression by promoting polyubiquitination and proteasomal degradation of HDAC1 protein (without affecting HDAC1 mRNA), thereby derepressing the maspin promoter; knockdown of maspin abrogates IFIXα-mediated suppression of breast cancer cell invasion.","method":"siRNA knockdown, Western blot, HDAC1 ubiquitination assay, proteasome inhibitor rescue, promoter reporter assay","journal":"Molecular carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 — ubiquitination assay plus proteasome rescue plus epistasis knockdown, single lab","pmids":["18247378"],"is_preprint":false},{"year":2020,"finding":"Class I HDACs (HDAC1 and HDAC8) repress maspin in prostate cancer cells independently of promoter DNA hypermethylation; HDAC inhibitors (sodium butyrate, TSA) restore maspin expression accompanied by increased H3/H4 acetylation and p53 enrichment at the maspin promoter, leading to suppression of proliferation and migration.","method":"HDAC inhibitor treatment, Western blot, ChIP (H3/H4 acetylation, p53 occupancy), RT-PCR, proliferation and migration assays","journal":"Molecular carcinogenesis","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus pharmacological intervention with functional readouts, single lab","pmids":["32391971"],"is_preprint":false},{"year":2017,"finding":"Maspin is secreted as an exosomal cargo protein encapsulated within the exosomal membrane; maspin knockdown in MCF-10A cells produces maspin-devoid exosomes with significantly reduced suppressive effects on chemotaxis of recipient NIH3T3 fibroblasts, demonstrating a paracrine tumor-suppressive function of exosomal maspin.","method":"Exosome isolation, electron microscopy, atomic force microscopy, Western blot, maspin shRNA knockdown, NIH3T3 chemotaxis assay","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 — direct visualization of exosomal maspin plus functional knockdown with defined readout, single lab","pmids":["28009978"],"is_preprint":false},{"year":2014,"finding":"Exogenously applied recombinant maspin (rMaspin) is internalized by multiple endocytic pathways into endosomal/lysosomal vesicles in cancer cells, as shown by real-time laser scanning confocal microscopy with dye-labeled protein; this lysosomal processing reduces biological activity of exogenous maspin compared with endogenously re-expressed maspin.","method":"Time-lapse laser scanning confocal microscopy with fluorescently labeled rMaspin, endocytic pathway inhibitors, co-localization with endosomal/lysosomal markers","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2 — direct live-cell imaging of protein trafficking with functional implication, single lab","pmids":["25256709"],"is_preprint":false},{"year":2021,"finding":"Cytoplasmic maspin in aggressive breast cancer cells (MDA-MB-231) promotes cell proliferation and invasion by upregulating SRGN, activating TGFβ signaling, and inducing EMT markers (N-cadherin and EMT transcription factors); nuclear maspin in normal epithelial cells has the opposite tumor-suppressive function.","method":"Stable maspin overexpression/knockdown in MDA-MB-231, Western blot for EMT markers and TGFβ pathway, SRGN protein level measurement, proliferation and invasion assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — gain- and loss-of-function with pathway-level readouts, single lab","pmids":["34059749"],"is_preprint":false},{"year":2024,"finding":"SERPINB5 overexpression in CRC cells activates the TNF-α/NF-κB pathway (upregulating p-NF-κB/p65, TNF-α, N-cadherin, MMP2, MMP9, VEGFA; downregulating E-cadherin), promoting EMT, angiogenesis, and invasion/migration; these effects are reversed by QNZ, a specific NF-κB inhibitor.","method":"Lentiviral overexpression and knockdown, Western blot, migration/invasion/proliferation assays, HUVEC tube formation assay, NF-κB inhibitor (QNZ) rescue","journal":"International immunopharmacology","confidence":"Medium","confidence_rationale":"Tier 2 — gain- and loss-of-function with pharmacological pathway validation, single lab","pmids":["38460302"],"is_preprint":false},{"year":2001,"finding":"Maspin is synthesized by normal human corneal stromal cells (the first non-epithelial cell type shown to do so); exogenous recombinant maspin increases adhesion of late-passage (maspin-negative) corneal stromal cells to fibronectin, type I collagen, type IV collagen, and laminin.","method":"Western blot, RT-PCR, immunofluorescence microscopy, recombinant maspin adhesion assay on multiple ECM substrates","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 — direct functional assay with recombinant protein in defined loss-of-expression system, single lab","pmids":["11726614"],"is_preprint":false},{"year":2015,"finding":"HBx (hepatitis B virus X protein) induces miR-7, miR-107, and miR-21 which directly target maspin mRNA, reducing maspin protein and promoting HCC cell motility and resistance to anoikis and chemotherapy.","method":"miRNA overexpression/inhibition, luciferase reporter for miRNA-target validation, HBx overexpression, Western blot, cell motility and anoikis assays","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 — direct miRNA targeting validated by reporter assay plus functional consequence, single lab","pmids":["26296971"],"is_preprint":false}],"current_model":"SERPINB5 (maspin) is a non-classical serpin that lacks direct serine protease inhibitory activity yet suppresses tumor invasion, metastasis, and angiogenesis through multiple context-dependent mechanisms: extracellularly it binds pro-uPA via its reactive site loop (RSL) and an exosite to inhibit plasmin-mediated uPA activation and stabilize focal adhesions; its G α-helix mediates inhibition of cell migration through β1-integrin-dependent interactions; intracellularly it inhibits HDAC1 (promoting Ku70 acetylation and Bax-mediated apoptosis and influencing gene expression), suppresses Rac1/Cdc42 GTPase activity via the RSL to inhibit motility, and modulates Bcl-2/Bax balance and AKT/FAK signaling to sensitize cells to apoptosis; its transcription is activated by p53/p63 and TAM-bound ERα and repressed by nuclear IKKα (downstream of RANKL/RANK), Snail, and PAR-1 (via CBP/p300 and chromatin remodeling), while its promoter is epigenetically silenced by CpG methylation and histone deacetylation in many cancers."},"narrative":{"teleology":[{"year":2000,"claim":"Establishing the transcriptional control of maspin by p53 answered how a known tumor suppressor directly regulates maspin expression, linking maspin to the DNA-damage response network.","evidence":"Promoter reporter assays, EMSA, and RT-PCR in prostate and breast cancer cells with wild-type vs. mutant p53","pmids":["10692390"],"confidence":"High","gaps":["No in vivo confirmation of p53-dependent maspin induction","Chromatin context of p53 binding not addressed"]},{"year":2002,"claim":"Demonstrating that maspin silencing in breast cancer results from CpG promoter methylation and histone deacetylation explained why maspin is lost in tumors despite an intact gene, establishing epigenetic regulation as the primary silencing mechanism.","evidence":"5-aza-dC and TSA treatment restoring maspin expression in maspin-negative breast cancer lines, with promoter reporter assays","pmids":["12220518","14670180"],"confidence":"High","gaps":["Methyltransferase(s) responsible not identified","Mechanism linking methylation to histone deacetylation at the maspin locus not resolved"]},{"year":2003,"claim":"Showing that maspin suppresses ECM degradation, angiogenesis, and osteolysis in vivo and inhibits Rac1 signaling established both extracellular and intracellular effector mechanisms for maspin's tumor-suppressive activity.","evidence":"In vitro ECM degradation assays, DU145 xenograft in human bone implants, Rac1 pull-down and PI3K inhibitor studies in MDA-MB-231 cells","pmids":["12788977","14508113"],"confidence":"High","gaps":["Direct molecular target mediating Rac1 inhibition not identified","Whether extracellular and intracellular functions are separable in vivo remained unclear"]},{"year":2004,"claim":"Identifying TAp63 as a maspin transcriptional activator and tamoxifen-bound ERα as an inducer expanded the network of upstream regulators beyond p53, connecting maspin to differentiation and hormonal signaling.","evidence":"ChIP and EMSA for p63 binding at the p53 site; ERα domain-deletion promoter reporter analysis","pmids":["15466179","15145521"],"confidence":"High","gaps":["In vivo relevance of ERα-mediated maspin induction not tested","Relative contribution of p53 vs. p63 in different tissues undefined"]},{"year":2005,"claim":"Demonstrating that maspin shifts Bcl-2/Bax balance and induces endothelial apoptosis via its RSL established maspin as a direct pro-apoptotic effector with anti-angiogenic consequences.","evidence":"Maspin overexpression in mammary tumor cells and adenoviral delivery to endothelial cells in tumor-bearing mice, with caspase inhibitor and Bcl-2 rescue","pmids":["15907209","15688005"],"confidence":"High","gaps":["Direct protein target mediating Bcl-2 downregulation not identified","Whether RSL-dependent apoptosis requires protease interaction or a distinct target unknown"]},{"year":2006,"claim":"Biochemical demonstration that maspin binds pro-uPA through its RSL (Arg340-dependent, Kd ~270 nM) and subsequently through an exosite resolved how maspin inhibits plasminogen activation without classical serpin mechanism.","evidence":"Fluorescence binding assays, R340A mutagenesis, co-localization with uPA/uPAR/LRP, tPA binding to S195A mutant","pmids":["16618739","17510061"],"confidence":"High","gaps":["Crystal structure of maspin–uPA complex lacking","Contribution of exosite vs. RSL binding to in vivo anti-metastatic activity not dissected"]},{"year":2007,"claim":"Identifying nuclear IKKα as a RANKL-induced repressor of maspin in vivo — with genetic epistasis showing maspin loss restores metastasis — provided a direct causal link between NF-κB pathway activation and maspin-dependent metastasis suppression.","evidence":"IKKα knock-in mutation in TRAMP prostate cancer model; maspin ablation rescue of metastasis","pmids":["17377533"],"confidence":"High","gaps":["Mechanism by which nuclear IKKα represses maspin promoter not fully elucidated","Whether IKKα directly modifies maspin chromatin or acts through intermediary transcription factors unclear"]},{"year":2007,"claim":"Demonstrating RSL-dependent inhibition of Rac1 and Cdc42 (but not RhoA) with downstream JNK/AP-1 suppression clarified the intracellular signaling mechanism by which maspin controls cell migration.","evidence":"GTPase pull-down, RSL deletion/point mutants, immuno-kinase and AP-1 reporter assays in mammary tumor cells","pmids":["17301947"],"confidence":"High","gaps":["Whether maspin directly binds Rac1/Cdc42 or acts through a GAP/GEF not resolved","Structural basis for RSL-mediated GTPase inhibition unknown"]},{"year":2010,"claim":"Mapping the G α-helix as necessary and sufficient for migration inhibition through β1-integrin dependence identified a second functional surface on maspin distinct from the RSL, resolving how maspin engages the adhesion machinery.","evidence":"G-helix point mutants, 15-mer peptide reconstitution, β1-integrin blocking antibody in migration and adhesion assays","pmids":["20837467"],"confidence":"High","gaps":["Direct binding partner on integrin or integrin-associated complex not identified","Relationship between G-helix and RSL functions in vivo not addressed"]},{"year":2011,"claim":"Showing that maspin directly inhibits HDAC1 to increase Ku70 acetylation and liberate Bax for mitochondrial apoptosis provided a mechanistic basis for maspin's intracellular pro-apoptotic function and connected it to epigenetic regulation.","evidence":"Co-IP of maspin with Ku70, HDAC1 activity assay, Ku70 acetylation and Bax dissociation measurements","pmids":["22076034"],"confidence":"Medium","gaps":["Direct maspin–HDAC1 binding interface not mapped","Whether maspin inhibits other HDACs not tested","Single-lab finding without independent replication"]},{"year":2012,"claim":"Identifying Snail as a direct transcriptional repressor and showing maspin regulates CDC25C/CDK1-dependent cell cycle progression expanded maspin's functional repertoire beyond migration and apoptosis to include proliferation control and EMT transcription factor crosstalk.","evidence":"ChIP for Snail at maspin promoter; maspin shRNA/overexpression with CDC25C/CDK1 phosphorylation readouts in gastric cancer cells","pmids":["22857708","22962304"],"confidence":"Medium","gaps":["Whether cell-cycle regulation is a primary or secondary effect of maspin unclear","Direct molecular link between maspin and CDC25C/CDK1 not established"]},{"year":2017,"claim":"Discovery that maspin is secreted within exosomes and that exosomal maspin suppresses fibroblast chemotaxis revealed a paracrine tumor-suppressive mechanism extending maspin's action to the tumor microenvironment.","evidence":"Exosome isolation with EM/AFM, maspin knockdown producing maspin-devoid exosomes, NIH3T3 chemotaxis assay","pmids":["28009978"],"confidence":"Medium","gaps":["Exosomal maspin cargo sorting mechanism unknown","In vivo relevance of exosomal maspin not tested","Single-lab finding"]},{"year":2021,"claim":"Demonstrating that cytoplasmic maspin in aggressive breast cancer promotes EMT via SRGN/TGFβ activation while nuclear maspin is tumor-suppressive revealed context-dependent, subcellular-localization-determined duality in maspin function.","evidence":"Stable maspin overexpression/knockdown in MDA-MB-231 with EMT marker and TGFβ pathway analysis","pmids":["34059749"],"confidence":"Medium","gaps":["Mechanism controlling nuclear vs. cytoplasmic partitioning not identified","How cytoplasmic maspin activates SRGN/TGFβ not defined","Single-lab observation in one cell line"]},{"year":2024,"claim":"Showing that SERPINB5 overexpression in colorectal cancer activates TNF-α/NF-κB signaling to promote EMT and angiogenesis reinforced the emerging model that maspin can have oncogenic functions in specific cellular contexts.","evidence":"Lentiviral overexpression/knockdown in CRC cells, NF-κB inhibitor (QNZ) rescue, HUVEC tube formation assay","pmids":["38460302"],"confidence":"Medium","gaps":["Mechanism linking maspin to TNF-α/NF-κB activation not identified","Apparent contradiction with classic tumor-suppressive role not reconciled at molecular level","Single-lab study"]},{"year":null,"claim":"Key unresolved questions include: how subcellular localization determines tumor-suppressive vs. oncogenic function; whether maspin directly binds Rac1/Cdc42 or HDAC1 and through which structural surfaces; and the structural basis for non-inhibitory serpin activity in vivo.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal structure of maspin in complex with any of its functional partners","Nuclear vs. cytoplasmic sorting mechanism unknown","No unified model reconciling tumor-suppressive and tumor-promoting activities across tissue types"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,4,6,11]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[11]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[3,4,24,28]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6,8,10,26]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[11,26]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[24,25]}],"pathway":[{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[8,9,11]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6,10,12,27]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[5,28]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,1,2,14,15]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[19,20,23]}],"complexes":[],"partners":["PLAU","PLAT","HDAC1","KHDRBS3","FBXO32","ITGB1"],"other_free_text":[]},"mechanistic_narrative":"SERPINB5 (maspin) is a non-inhibitory serpin that functions as a tumor suppressor by integrating extracellular protease regulation, intracellular signaling modulation, and pro-apoptotic activity across epithelial and endothelial contexts. Extracellularly, maspin binds pro-uPA via its reactive site loop (RSL) and a distinct exosite (Kd ~270–600 nM), inhibiting plasmin-mediated uPA activation, stabilizing focal adhesions, and suppressing ECM degradation, while its G α-helix mediates β1-integrin-dependent inhibition of cell migration [PMID:16618739, PMID:17510061, PMID:20837467]. Intracellularly, maspin suppresses Rac1/Cdc42 GTPase activity through the RSL to inhibit motility, directly inhibits HDAC1 to promote Ku70 acetylation and Bax-dependent apoptosis, modulates Bcl-2/Bax balance and AKT/FAK signaling, and induces endothelial cell apoptosis to block tumor angiogenesis [PMID:17301947, PMID:22076034, PMID:15907209, PMID:15688005]. Transcription of SERPINB5 is activated by p53 and TAp63 binding its promoter and is epigenetically silenced through CpG methylation and histone deacetylation in multiple cancer types, with additional repression by nuclear IKKα (RANKL-dependent), Snail, and PAR-1 signaling [PMID:10692390, PMID:15466179, PMID:17377533, PMID:14670180, PMID:22857708, PMID:21187389]."},"prefetch_data":{"uniprot":{"accession":"P36952","full_name":"Serpin B5","aliases":["Maspin","Peptidase inhibitor 5","PI-5"],"length_aa":375,"mass_kda":42.1,"function":"Tumor suppressor. It blocks the growth, invasion, and metastatic properties of mammary tumors. As it does not undergo the S (stressed) to R (relaxed) conformational transition characteristic of active serpins, it exhibits no serine protease inhibitory activity","subcellular_location":"Secreted, extracellular space","url":"https://www.uniprot.org/uniprotkb/P36952/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SERPINB5","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SERPINB5","total_profiled":1310},"omim":[{"mim_id":"600518","title":"SERPIN PEPTIDASE INHIBITOR, CLADE B (OVALBUMIN), MEMBER 4; SERPINB4","url":"https://www.omim.org/entry/600518"},{"mim_id":"600517","title":"SERPIN PEPTIDASE INHIBITOR, CLADE B (OVALBUMIN), MEMBER 3; 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medicine","url":"https://pubmed.ncbi.nlm.nih.gov/18698492","citation_count":19,"is_preprint":false},{"pmid":"22963136","id":"PMC_22963136","title":"Possible predictive value of maspin expression in colorectal cancer.","date":"2013","source":"Recent patents on anti-cancer drug discovery","url":"https://pubmed.ncbi.nlm.nih.gov/22963136","citation_count":18,"is_preprint":false},{"pmid":"14534696","id":"PMC_14534696","title":"Maspin in thyroid cancer: its relationship with p53 and clinical outcome.","date":"2003","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/14534696","citation_count":18,"is_preprint":false},{"pmid":"22076034","id":"PMC_22076034","title":"Maspin increases Ku70 acetylation and Bax-mediated cell death in cancer cells.","date":"2011","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/22076034","citation_count":17,"is_preprint":false},{"pmid":"22825520","id":"PMC_22825520","title":"Predictive value of maspin and Ki-67 expression in transurethral resection specimens in patients with T1 bladder cancer.","date":"2012","source":"Tumori","url":"https://pubmed.ncbi.nlm.nih.gov/22825520","citation_count":17,"is_preprint":false},{"pmid":"25256709","id":"PMC_25256709","title":"Internalization by multiple endocytic pathways and lysosomal processing impact maspin-based therapeutics.","date":"2014","source":"Molecular cancer research : MCR","url":"https://pubmed.ncbi.nlm.nih.gov/25256709","citation_count":17,"is_preprint":false},{"pmid":"31564075","id":"PMC_31564075","title":"Pi5 and Pii Paired NLRs Are Functionally Exchangeable and Confer Similar Disease Resistance Specificity.","date":"2019","source":"Molecules and cells","url":"https://pubmed.ncbi.nlm.nih.gov/31564075","citation_count":16,"is_preprint":false},{"pmid":"17510061","id":"PMC_17510061","title":"Maspin binds to urokinase-type and tissue-type plasminogen activator through exosite-exosite interactions.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17510061","citation_count":16,"is_preprint":false},{"pmid":"17912078","id":"PMC_17912078","title":"Maspin expression in oral squamous cell carcinoma.","date":"2007","source":"The Journal of craniofacial surgery","url":"https://pubmed.ncbi.nlm.nih.gov/17912078","citation_count":15,"is_preprint":false},{"pmid":"16044948","id":"PMC_16044948","title":"Maspin and c-erbB-2 expression in correlation with microvessel density in invasive ductal breast cancer.","date":"2005","source":"Folia histochemica et cytobiologica","url":"https://pubmed.ncbi.nlm.nih.gov/16044948","citation_count":15,"is_preprint":false},{"pmid":"18247378","id":"PMC_18247378","title":"Interferon-inducible protein IFIXalpha inhibits cell invasion by upregulating the metastasis suppressor maspin.","date":"2008","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/18247378","citation_count":15,"is_preprint":false},{"pmid":"16751302","id":"PMC_16751302","title":"Simultaneous evaluation of maspin and CXCR4 in patients with breast cancer.","date":"2006","source":"Journal of clinical pathology","url":"https://pubmed.ncbi.nlm.nih.gov/16751302","citation_count":15,"is_preprint":false},{"pmid":"18665036","id":"PMC_18665036","title":"Cytoplasmic and nuclear maspin expression in lung carcinomas: an immunohistochemical study using tissue microarrays.","date":"2008","source":"Applied immunohistochemistry & molecular morphology : AIMM","url":"https://pubmed.ncbi.nlm.nih.gov/18665036","citation_count":14,"is_preprint":false},{"pmid":"16918974","id":"PMC_16918974","title":"Nuclear maspin detection in renal cell tumours: possible diagnostic role and correlation with p53 status.","date":"2006","source":"Histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/16918974","citation_count":14,"is_preprint":false},{"pmid":"15353283","id":"PMC_15353283","title":"Multiple functions of maspin in tumor progression and mouse development.","date":"2004","source":"Frontiers in bioscience : a journal and virtual library","url":"https://pubmed.ncbi.nlm.nih.gov/15353283","citation_count":14,"is_preprint":false},{"pmid":"34059749","id":"PMC_34059749","title":"Role of cytoplasmic localization of maspin in promoting cell invasion in breast cancer with aggressive phenotype.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/34059749","citation_count":14,"is_preprint":false},{"pmid":"39082173","id":"PMC_39082173","title":"miR-1204 Positioning in 8q24.21 Involved in the Tumorigenesis of Colorectal Cancer by Targeting MASPIN.","date":"2024","source":"Protein and peptide letters","url":"https://pubmed.ncbi.nlm.nih.gov/39082173","citation_count":14,"is_preprint":false},{"pmid":"23140166","id":"PMC_23140166","title":"Tumor suppressor maspin as a rheostat in HDAC regulation to achieve the fine-tuning of epithelial homeostasis.","date":"2012","source":"Critical reviews in eukaryotic gene expression","url":"https://pubmed.ncbi.nlm.nih.gov/23140166","citation_count":14,"is_preprint":false},{"pmid":"25151033","id":"PMC_25151033","title":"Promoter hypomethylation and increased maspin expression in preeclamptic placentas in a Chinese population.","date":"2014","source":"Placenta","url":"https://pubmed.ncbi.nlm.nih.gov/25151033","citation_count":13,"is_preprint":false},{"pmid":"17376297","id":"PMC_17376297","title":"Gum mastic increases maspin expression in prostate cancer cells.","date":"2007","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/17376297","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47887,"output_tokens":6960,"usd":0.124031},"stage2":{"model":"claude-opus-4-6","input_tokens":10773,"output_tokens":3663,"usd":0.21816},"total_usd":0.342191,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"Wild-type p53 directly activates maspin transcription by binding to a p53 consensus-binding site in the maspin promoter, as demonstrated by promoter reporter assays and gel-shift experiments; DNA-damaging agents induced maspin expression in cells with wild-type p53 but not mutant p53.\",\n      \"method\": \"Adenoviral p53 overexpression, promoter reporter assay, gel-shift (EMSA), RT-PCR in prostate and breast cancer cell lines\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (EMSA, promoter reporter, functional rescue), replicated across multiple cell lines\",\n      \"pmids\": [\"10692390\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"p63 (specifically TAp63) is a critical transcriptional activator of maspin in lung cancer cells, binding to the previously identified p53-binding site on the maspin promoter, as shown by gel-shift and chromatin immunoprecipitation assays.\",\n      \"method\": \"Transient transfection, promoter reporter assay, EMSA, ChIP\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — orthogonal methods (ChIP + EMSA + reporter assay) in a single rigorous study\",\n      \"pmids\": [\"15466179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Nuclear IKKα activated by RANKL represses maspin transcription in prostate epithelial cells; a mutation preventing IKKα activation led to elevated maspin expression and reduced metastasis in TRAMP mice, with ablation of maspin restoring metastatic activity.\",\n      \"method\": \"Genetic mouse model (TRAMP), IKKα knock-in mutation, nuclear IKKα translocation assay, epistasis rescue experiment\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vivo genetic epistasis in mouse model plus molecular rescue, high-citation foundational study\",\n      \"pmids\": [\"17377533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Maspin binds to pro-uPA (K_d ~270 nM) via its reactive site loop (RSL), with Arg340 (P1' site) critical for binding; this interaction inhibits plasmin-mediated pro-uPA cleavage and promotes internalization of uPA/uPAR, thereby stabilizing focal adhesion contacts and retarding cell detachment.\",\n      \"method\": \"Biochemical binding assay (fluorescence), site-directed mutagenesis (R340A), co-localization, cell detachment assay, LRP co-IP\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct binding measured with K_d, mutagenesis confirming critical residue, multiple orthogonal functional assays\",\n      \"pmids\": [\"16618739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Maspin binds uPA and tPA through an exosite on maspin near but outside its reactive center loop, with K_d values 300–600 nM; the binding site on tPA does not involve the proteinase active site, and RCL mutation (Arg340) does not abolish binding, indicating exosite–exosite interactions.\",\n      \"method\": \"Fluorescence binding assays (intrinsic and extrinsic), RCL mutagenesis, binding to S195A tPA already complexed with PAI-1\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct biophysical binding measurement with mutagenesis dissecting binding site\",\n      \"pmids\": [\"17510061\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The G α-helix of maspin is essential and sufficient for inhibiting cell migration and mediating effects on cell adhesion; these effects are dependent on β1 integrins, as demonstrated by point mutations and a 15-mer G-helix peptide mimicking full-length maspin activity.\",\n      \"method\": \"Site-directed mutagenesis, peptide reconstitution, cell migration assay, cell adhesion assay, β1-integrin blocking\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mutagenesis + peptide reconstitution + integrin blocking providing convergent mechanistic evidence\",\n      \"pmids\": [\"20837467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Maspin inhibits Rac1 and Cdc42 GTPase activity (but not RhoA) to control mammary tumor cell migration; the reactive site loop (RSL) of maspin is required for this inhibition, and downstream JNK kinase activity and AP-1 transcription are suppressed.\",\n      \"method\": \"GST-PAK and GST-Rho binding pull-down for GTP-bound GTPases, RSL deletion/point-mutation analysis, immuno-kinase assay, AP-1 reporter assay\",\n      \"journal\": \"Cell motility and the cytoskeleton\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct GTPase pull-down plus mutagenesis plus downstream signaling readouts\",\n      \"pmids\": [\"17301947\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Maspin inhibits uPA-mediated extracellular matrix degradation and collagen remodeling in vitro, and maspin-expressing DU145 prostate cancer cells injected into human fetal bone implants show decreased tumor growth, reduced osteolysis, decreased angiogenesis, increased fibrosis, and glandular redifferentiation in vivo.\",\n      \"method\": \"In vitro ECM/collagen degradation assays, maspin-transfectant xenograft model in immunodeficient mice with human fetal bone\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean gain-of-function in vivo model with specific phenotypic readouts (osteolysis, angiogenesis, fibrosis)\",\n      \"pmids\": [\"12788977\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Maspin overexpression reduces Bcl-2 protein levels and increases Bax protein levels post-translationally, leading to increased cytochrome c release and apoptosis in mammary tumor cells under staurosporine and serum starvation; the effect is intracellular and is partially blocked by caspase-8 and caspase-9 inhibitors.\",\n      \"method\": \"Stable maspin-expressing transfectants, TUNEL assay, Western blot, RPA for Bcl-2 family, caspase inhibitor experiments\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO/OE with multiple readouts but single lab\",\n      \"pmids\": [\"15907209\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Targeted intravascular expression of maspin in endothelial cells induces endothelial cell apoptosis in vitro and in vivo, disrupting tumor-induced angiogenesis; the pro-apoptotic effect requires the RSL region of maspin and is accompanied by changes in Bcl-2 family gene expression and is blocked by caspase inhibitors and Bcl-2 overexpression.\",\n      \"method\": \"Adenoviral maspin delivery in mice bearing mammary tumors, in vitro HUVEC apoptosis assay, RSL-deletion mutant, Bcl-2 overexpression rescue, caspase inhibitor experiments\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vivo delivery plus in vitro mechanistic dissection with mutagenesis and genetic rescue\",\n      \"pmids\": [\"15688005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Maspin regulates cell motility through the Rho GTPase pathway: exogenous recombinant maspin decreases Rac1 activity within 4 h and reduces its effector PAK1 within 12 h in MDA-MB-231 breast cancer cells; adhesion increase is mediated by PI3K/ERK pathways and is abrogated by LY294002.\",\n      \"method\": \"Recombinant maspin treatment, stable transfection, Rac1 pull-down, PI3K inhibitor (LY294002), ERK kinase assay, focal adhesion staining\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple signaling readouts with pharmacological epistasis, single lab\",\n      \"pmids\": [\"14508113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Maspin directly inhibits HDAC1, increasing Ku70 acetylation and dissociation of Bax from Ku70, thereby promoting Bax translocation to mitochondria and apoptosis in cancer cells.\",\n      \"method\": \"Co-IP (maspin–Ku70 interaction), HDAC1 activity assay, Ku70 acetylation Western blot, Bax–Ku70 dissociation assay, cell death measurements\",\n      \"journal\": \"International journal of molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical interaction plus functional consequence, single lab\",\n      \"pmids\": [\"22076034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Maspin suppresses hypoxia-induced prostate cancer cell survival and tumor vascularity by targeting Akt and focal adhesion kinase (FAK) activation, as shown in maspin-overexpressing DU-145 cells exposed to 1% O₂ and in in vivo tumor studies.\",\n      \"method\": \"Maspin-overexpressing stable transfectants, hypoxia exposure (1% O₂), Akt/FAK phosphorylation Western blot, in vivo tumor implantation\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function in vitro and in vivo with signaling readouts, single lab\",\n      \"pmids\": [\"18931702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In response to hypoxia, cytoplasmic PTEN prevents Mdm2 nuclear localization (by attenuating Akt) while nuclear PTEN complexes with p53 to coordinately induce maspin transcription; loss of PTEN or p53 individually attenuates hypoxia-induced maspin expression in glioblastoma cells.\",\n      \"method\": \"PTEN/p53 knockdown and reconstitution in U87 cells, subcellular fractionation, Co-IP (PTEN–p53 complex), in vivo xenograft IHC\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with Co-IP and in vivo validation, single lab\",\n      \"pmids\": [\"19221500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Snail transcription factor directly represses maspin promoter activity by binding to the maspin promoter, as confirmed by ChIP; Snail overexpression increases and Snail knockdown decreases maspin expression, with corresponding changes in migration and invasion in prostate cancer cells.\",\n      \"method\": \"Luciferase reporter assay, ChIP, RT-PCR, Western blot, siRNA knockdown, stable overexpression, migration/invasion assays\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus reporter plus functional assays, single lab\",\n      \"pmids\": [\"22857708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PAR-1 (thrombin receptor) negatively regulates maspin transcription in metastatic melanoma by decreasing binding of Ets-1 and c-Jun to the maspin promoter via reduced CBP/p300 levels and increased p38 activity; PAR-1 silencing restored maspin expression, reduced invasion, tumor growth, and experimental lung metastasis.\",\n      \"method\": \"PAR-1 siRNA nanoliposome delivery, ChIP for Ets-1/c-Jun at maspin promoter, CBP/p300 and p38 expression analysis, in vivo lung metastasis model, maspin rescue experiments\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — ChIP, in vivo epistasis rescue, and multiple orthogonal methods in a single study\",\n      \"pmids\": [\"21187389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Maspin regulates cell cycle progression by influencing CDC25C and CDK1 activity; maspin downregulation (by shRNA or E2F1-DP1 overexpression) in MKN45 cells accelerated cell cycle progression with increased active CDC25C and decreased inactive CDK1, while maspin upregulation had the opposite effect.\",\n      \"method\": \"shRNA knockdown, stable overexpression, cell cycle analysis, CDC25C/CDK1 phosphorylation Western blot, promoter haplotype reporter assay\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain- and loss-of-function with defined molecular readouts, single lab\",\n      \"pmids\": [\"22962304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"SerpinB5/maspin interacts with KHDRBS3 and FBXO32 in gastric cancer cells, as identified by yeast two-hybrid screening and validated by co-immunoprecipitation; KHDRBS3 also interacts with FBXO32 mRNA (RNA Co-IP), and changes in SerpinB5 expression affect FBXO32 mRNA levels through KHDRBS3 protein.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, RNA co-immunoprecipitation, Western blot, real-time PCR\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — reciprocal Co-IP plus RNA Co-IP, but functional consequences of complex incompletely established\",\n      \"pmids\": [\"21725612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"A Pro176Ser polymorphism in maspin located near the reactive site loop reduces its tumor suppressor function: cells expressing Ser176 maspin showed decreased apoptosis, increased colony formation, and higher in vivo tumor formation rate compared to Pro176 maspin.\",\n      \"method\": \"Stable expression of polymorphic variants, apoptosis assay, colony formation assay, mouse tumor formation assay, structural modeling\",\n      \"journal\": \"International journal of molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct functional comparison of polymorphic variants in vitro and in vivo, single lab\",\n      \"pmids\": [\"18698492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Maspin gene silencing in breast cancer cells is caused by CpG promoter hypermethylation and histone deacetylation; treatment with 5-aza-2'-deoxycytidine and/or trichostatin A restores maspin promoter activity and expression in maspin-negative breast cancer cell lines.\",\n      \"method\": \"Promoter reporter assay, 5-aza-dC treatment, TSA treatment, RT-PCR\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological demethylation/HDAC inhibition experiments with promoter reporter, replicated in multiple cell lines\",\n      \"pmids\": [\"12220518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Maspin expression in human pancreatic carcinoma cells is activated by epigenetic derepression: maspin-positive pancreatic cancer cells have unmethylated promoters with hyperacetylated H3/H4 histones, whereas maspin-negative cells have methylated promoters with hypoacetylated histones; 5-aza-dC treatment activates maspin in negative lines.\",\n      \"method\": \"Bisulfite genomic sequencing, ChIP (H3/H4 acetylation), 5-aza-dC treatment, RT-PCR\",\n      \"journal\": \"Neoplasia (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — bisulfite sequencing + ChIP + pharmacological intervention, orthogonal epigenetic characterization\",\n      \"pmids\": [\"14670180\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Tamoxifen induces maspin expression through estrogen receptor alpha (ERα) but not ERβ; the ERα N-terminal AF-1 domain is required for basal maspin transcription and the LBD-AF2 domain is required for tamoxifen-induced activation; binding occurs via cofactor recruitment to a region between -90 and +87 bp, not through the HRE site.\",\n      \"method\": \"Promoter reporter assay, ERα/ERβ reconstitution, ERα deletion/point mutants, transient transfection in multiple cell lines\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic domain mutant analysis with reporter assay, single lab\",\n      \"pmids\": [\"15145521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"IFIXα induces maspin expression by promoting polyubiquitination and proteasomal degradation of HDAC1 protein (without affecting HDAC1 mRNA), thereby derepressing the maspin promoter; knockdown of maspin abrogates IFIXα-mediated suppression of breast cancer cell invasion.\",\n      \"method\": \"siRNA knockdown, Western blot, HDAC1 ubiquitination assay, proteasome inhibitor rescue, promoter reporter assay\",\n      \"journal\": \"Molecular carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ubiquitination assay plus proteasome rescue plus epistasis knockdown, single lab\",\n      \"pmids\": [\"18247378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Class I HDACs (HDAC1 and HDAC8) repress maspin in prostate cancer cells independently of promoter DNA hypermethylation; HDAC inhibitors (sodium butyrate, TSA) restore maspin expression accompanied by increased H3/H4 acetylation and p53 enrichment at the maspin promoter, leading to suppression of proliferation and migration.\",\n      \"method\": \"HDAC inhibitor treatment, Western blot, ChIP (H3/H4 acetylation, p53 occupancy), RT-PCR, proliferation and migration assays\",\n      \"journal\": \"Molecular carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus pharmacological intervention with functional readouts, single lab\",\n      \"pmids\": [\"32391971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Maspin is secreted as an exosomal cargo protein encapsulated within the exosomal membrane; maspin knockdown in MCF-10A cells produces maspin-devoid exosomes with significantly reduced suppressive effects on chemotaxis of recipient NIH3T3 fibroblasts, demonstrating a paracrine tumor-suppressive function of exosomal maspin.\",\n      \"method\": \"Exosome isolation, electron microscopy, atomic force microscopy, Western blot, maspin shRNA knockdown, NIH3T3 chemotaxis assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct visualization of exosomal maspin plus functional knockdown with defined readout, single lab\",\n      \"pmids\": [\"28009978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Exogenously applied recombinant maspin (rMaspin) is internalized by multiple endocytic pathways into endosomal/lysosomal vesicles in cancer cells, as shown by real-time laser scanning confocal microscopy with dye-labeled protein; this lysosomal processing reduces biological activity of exogenous maspin compared with endogenously re-expressed maspin.\",\n      \"method\": \"Time-lapse laser scanning confocal microscopy with fluorescently labeled rMaspin, endocytic pathway inhibitors, co-localization with endosomal/lysosomal markers\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct live-cell imaging of protein trafficking with functional implication, single lab\",\n      \"pmids\": [\"25256709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cytoplasmic maspin in aggressive breast cancer cells (MDA-MB-231) promotes cell proliferation and invasion by upregulating SRGN, activating TGFβ signaling, and inducing EMT markers (N-cadherin and EMT transcription factors); nuclear maspin in normal epithelial cells has the opposite tumor-suppressive function.\",\n      \"method\": \"Stable maspin overexpression/knockdown in MDA-MB-231, Western blot for EMT markers and TGFβ pathway, SRGN protein level measurement, proliferation and invasion assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain- and loss-of-function with pathway-level readouts, single lab\",\n      \"pmids\": [\"34059749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SERPINB5 overexpression in CRC cells activates the TNF-α/NF-κB pathway (upregulating p-NF-κB/p65, TNF-α, N-cadherin, MMP2, MMP9, VEGFA; downregulating E-cadherin), promoting EMT, angiogenesis, and invasion/migration; these effects are reversed by QNZ, a specific NF-κB inhibitor.\",\n      \"method\": \"Lentiviral overexpression and knockdown, Western blot, migration/invasion/proliferation assays, HUVEC tube formation assay, NF-κB inhibitor (QNZ) rescue\",\n      \"journal\": \"International immunopharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain- and loss-of-function with pharmacological pathway validation, single lab\",\n      \"pmids\": [\"38460302\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Maspin is synthesized by normal human corneal stromal cells (the first non-epithelial cell type shown to do so); exogenous recombinant maspin increases adhesion of late-passage (maspin-negative) corneal stromal cells to fibronectin, type I collagen, type IV collagen, and laminin.\",\n      \"method\": \"Western blot, RT-PCR, immunofluorescence microscopy, recombinant maspin adhesion assay on multiple ECM substrates\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct functional assay with recombinant protein in defined loss-of-expression system, single lab\",\n      \"pmids\": [\"11726614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HBx (hepatitis B virus X protein) induces miR-7, miR-107, and miR-21 which directly target maspin mRNA, reducing maspin protein and promoting HCC cell motility and resistance to anoikis and chemotherapy.\",\n      \"method\": \"miRNA overexpression/inhibition, luciferase reporter for miRNA-target validation, HBx overexpression, Western blot, cell motility and anoikis assays\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct miRNA targeting validated by reporter assay plus functional consequence, single lab\",\n      \"pmids\": [\"26296971\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SERPINB5 (maspin) is a non-classical serpin that lacks direct serine protease inhibitory activity yet suppresses tumor invasion, metastasis, and angiogenesis through multiple context-dependent mechanisms: extracellularly it binds pro-uPA via its reactive site loop (RSL) and an exosite to inhibit plasmin-mediated uPA activation and stabilize focal adhesions; its G α-helix mediates inhibition of cell migration through β1-integrin-dependent interactions; intracellularly it inhibits HDAC1 (promoting Ku70 acetylation and Bax-mediated apoptosis and influencing gene expression), suppresses Rac1/Cdc42 GTPase activity via the RSL to inhibit motility, and modulates Bcl-2/Bax balance and AKT/FAK signaling to sensitize cells to apoptosis; its transcription is activated by p53/p63 and TAM-bound ERα and repressed by nuclear IKKα (downstream of RANKL/RANK), Snail, and PAR-1 (via CBP/p300 and chromatin remodeling), while its promoter is epigenetically silenced by CpG methylation and histone deacetylation in many cancers.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SERPINB5 (maspin) is a non-inhibitory serpin that functions as a tumor suppressor by integrating extracellular protease regulation, intracellular signaling modulation, and pro-apoptotic activity across epithelial and endothelial contexts. Extracellularly, maspin binds pro-uPA via its reactive site loop (RSL) and a distinct exosite (Kd ~270–600 nM), inhibiting plasmin-mediated uPA activation, stabilizing focal adhesions, and suppressing ECM degradation, while its G α-helix mediates β1-integrin-dependent inhibition of cell migration [PMID:16618739, PMID:17510061, PMID:20837467]. Intracellularly, maspin suppresses Rac1/Cdc42 GTPase activity through the RSL to inhibit motility, directly inhibits HDAC1 to promote Ku70 acetylation and Bax-dependent apoptosis, modulates Bcl-2/Bax balance and AKT/FAK signaling, and induces endothelial cell apoptosis to block tumor angiogenesis [PMID:17301947, PMID:22076034, PMID:15907209, PMID:15688005]. Transcription of SERPINB5 is activated by p53 and TAp63 binding its promoter and is epigenetically silenced through CpG methylation and histone deacetylation in multiple cancer types, with additional repression by nuclear IKKα (RANKL-dependent), Snail, and PAR-1 signaling [PMID:10692390, PMID:15466179, PMID:17377533, PMID:14670180, PMID:22857708, PMID:21187389].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing the transcriptional control of maspin by p53 answered how a known tumor suppressor directly regulates maspin expression, linking maspin to the DNA-damage response network.\",\n      \"evidence\": \"Promoter reporter assays, EMSA, and RT-PCR in prostate and breast cancer cells with wild-type vs. mutant p53\",\n      \"pmids\": [\"10692390\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No in vivo confirmation of p53-dependent maspin induction\", \"Chromatin context of p53 binding not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrating that maspin silencing in breast cancer results from CpG promoter methylation and histone deacetylation explained why maspin is lost in tumors despite an intact gene, establishing epigenetic regulation as the primary silencing mechanism.\",\n      \"evidence\": \"5-aza-dC and TSA treatment restoring maspin expression in maspin-negative breast cancer lines, with promoter reporter assays\",\n      \"pmids\": [\"12220518\", \"14670180\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Methyltransferase(s) responsible not identified\", \"Mechanism linking methylation to histone deacetylation at the maspin locus not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showing that maspin suppresses ECM degradation, angiogenesis, and osteolysis in vivo and inhibits Rac1 signaling established both extracellular and intracellular effector mechanisms for maspin's tumor-suppressive activity.\",\n      \"evidence\": \"In vitro ECM degradation assays, DU145 xenograft in human bone implants, Rac1 pull-down and PI3K inhibitor studies in MDA-MB-231 cells\",\n      \"pmids\": [\"12788977\", \"14508113\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular target mediating Rac1 inhibition not identified\", \"Whether extracellular and intracellular functions are separable in vivo remained unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identifying TAp63 as a maspin transcriptional activator and tamoxifen-bound ERα as an inducer expanded the network of upstream regulators beyond p53, connecting maspin to differentiation and hormonal signaling.\",\n      \"evidence\": \"ChIP and EMSA for p63 binding at the p53 site; ERα domain-deletion promoter reporter analysis\",\n      \"pmids\": [\"15466179\", \"15145521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of ERα-mediated maspin induction not tested\", \"Relative contribution of p53 vs. p63 in different tissues undefined\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrating that maspin shifts Bcl-2/Bax balance and induces endothelial apoptosis via its RSL established maspin as a direct pro-apoptotic effector with anti-angiogenic consequences.\",\n      \"evidence\": \"Maspin overexpression in mammary tumor cells and adenoviral delivery to endothelial cells in tumor-bearing mice, with caspase inhibitor and Bcl-2 rescue\",\n      \"pmids\": [\"15907209\", \"15688005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct protein target mediating Bcl-2 downregulation not identified\", \"Whether RSL-dependent apoptosis requires protease interaction or a distinct target unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Biochemical demonstration that maspin binds pro-uPA through its RSL (Arg340-dependent, Kd ~270 nM) and subsequently through an exosite resolved how maspin inhibits plasminogen activation without classical serpin mechanism.\",\n      \"evidence\": \"Fluorescence binding assays, R340A mutagenesis, co-localization with uPA/uPAR/LRP, tPA binding to S195A mutant\",\n      \"pmids\": [\"16618739\", \"17510061\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crystal structure of maspin–uPA complex lacking\", \"Contribution of exosite vs. RSL binding to in vivo anti-metastatic activity not dissected\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identifying nuclear IKKα as a RANKL-induced repressor of maspin in vivo — with genetic epistasis showing maspin loss restores metastasis — provided a direct causal link between NF-κB pathway activation and maspin-dependent metastasis suppression.\",\n      \"evidence\": \"IKKα knock-in mutation in TRAMP prostate cancer model; maspin ablation rescue of metastasis\",\n      \"pmids\": [\"17377533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which nuclear IKKα represses maspin promoter not fully elucidated\", \"Whether IKKα directly modifies maspin chromatin or acts through intermediary transcription factors unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrating RSL-dependent inhibition of Rac1 and Cdc42 (but not RhoA) with downstream JNK/AP-1 suppression clarified the intracellular signaling mechanism by which maspin controls cell migration.\",\n      \"evidence\": \"GTPase pull-down, RSL deletion/point mutants, immuno-kinase and AP-1 reporter assays in mammary tumor cells\",\n      \"pmids\": [\"17301947\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether maspin directly binds Rac1/Cdc42 or acts through a GAP/GEF not resolved\", \"Structural basis for RSL-mediated GTPase inhibition unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Mapping the G α-helix as necessary and sufficient for migration inhibition through β1-integrin dependence identified a second functional surface on maspin distinct from the RSL, resolving how maspin engages the adhesion machinery.\",\n      \"evidence\": \"G-helix point mutants, 15-mer peptide reconstitution, β1-integrin blocking antibody in migration and adhesion assays\",\n      \"pmids\": [\"20837467\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding partner on integrin or integrin-associated complex not identified\", \"Relationship between G-helix and RSL functions in vivo not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showing that maspin directly inhibits HDAC1 to increase Ku70 acetylation and liberate Bax for mitochondrial apoptosis provided a mechanistic basis for maspin's intracellular pro-apoptotic function and connected it to epigenetic regulation.\",\n      \"evidence\": \"Co-IP of maspin with Ku70, HDAC1 activity assay, Ku70 acetylation and Bax dissociation measurements\",\n      \"pmids\": [\"22076034\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct maspin–HDAC1 binding interface not mapped\", \"Whether maspin inhibits other HDACs not tested\", \"Single-lab finding without independent replication\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying Snail as a direct transcriptional repressor and showing maspin regulates CDC25C/CDK1-dependent cell cycle progression expanded maspin's functional repertoire beyond migration and apoptosis to include proliferation control and EMT transcription factor crosstalk.\",\n      \"evidence\": \"ChIP for Snail at maspin promoter; maspin shRNA/overexpression with CDC25C/CDK1 phosphorylation readouts in gastric cancer cells\",\n      \"pmids\": [\"22857708\", \"22962304\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether cell-cycle regulation is a primary or secondary effect of maspin unclear\", \"Direct molecular link between maspin and CDC25C/CDK1 not established\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Discovery that maspin is secreted within exosomes and that exosomal maspin suppresses fibroblast chemotaxis revealed a paracrine tumor-suppressive mechanism extending maspin's action to the tumor microenvironment.\",\n      \"evidence\": \"Exosome isolation with EM/AFM, maspin knockdown producing maspin-devoid exosomes, NIH3T3 chemotaxis assay\",\n      \"pmids\": [\"28009978\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Exosomal maspin cargo sorting mechanism unknown\", \"In vivo relevance of exosomal maspin not tested\", \"Single-lab finding\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrating that cytoplasmic maspin in aggressive breast cancer promotes EMT via SRGN/TGFβ activation while nuclear maspin is tumor-suppressive revealed context-dependent, subcellular-localization-determined duality in maspin function.\",\n      \"evidence\": \"Stable maspin overexpression/knockdown in MDA-MB-231 with EMT marker and TGFβ pathway analysis\",\n      \"pmids\": [\"34059749\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism controlling nuclear vs. cytoplasmic partitioning not identified\", \"How cytoplasmic maspin activates SRGN/TGFβ not defined\", \"Single-lab observation in one cell line\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showing that SERPINB5 overexpression in colorectal cancer activates TNF-α/NF-κB signaling to promote EMT and angiogenesis reinforced the emerging model that maspin can have oncogenic functions in specific cellular contexts.\",\n      \"evidence\": \"Lentiviral overexpression/knockdown in CRC cells, NF-κB inhibitor (QNZ) rescue, HUVEC tube formation assay\",\n      \"pmids\": [\"38460302\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking maspin to TNF-α/NF-κB activation not identified\", \"Apparent contradiction with classic tumor-suppressive role not reconciled at molecular level\", \"Single-lab study\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: how subcellular localization determines tumor-suppressive vs. oncogenic function; whether maspin directly binds Rac1/Cdc42 or HDAC1 and through which structural surfaces; and the structural basis for non-inhibitory serpin activity in vivo.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal structure of maspin in complex with any of its functional partners\", \"Nuclear vs. cytoplasmic sorting mechanism unknown\", \"No unified model reconciling tumor-suppressive and tumor-promoting activities across tissue types\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 4, 6, 11]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [3, 4, 24, 28]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6, 8, 10, 26]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [11, 26]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [24, 25]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [8, 9, 11]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6, 10, 12, 27]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [5, 28]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 1, 2, 14, 15]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [19, 20, 23]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PLAU\",\n      \"PLAT\",\n      \"HDAC1\",\n      \"KHDRBS3\",\n      \"FBXO32\",\n      \"ITGB1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}